For various magnetic resonance examinations physicians prefer to have a survey first of the nuclear magnetization distribution in a three-dimensional volume. To achieve this there are methods where the volume is exposed to a plurality of sequences which comprise at least one RF pulse which acts on the entire volume. Such methods necessitate a very large dynamic range for the processing of the spin resonance signals produced in the volume and are rather time-consuming, because the magnetic gradient field which is switched on and off subsequent to each RF pulse must be varied in two mutually perpendicular directions from one sequence to another.
It is also known that the nuclear magnetization distribution in a three-dimensional region can be determining by measuring the nuclear magnetization in a number of adjoining parallel slices. The so-called multi-slice methods (see "Principles of MR imaging", published by Philips Medical Systems 1984, p. 48) result in short overall measuring times. According to these methods the repetition time which must elapse after a sequence before the next sequence can act on the same slice is used to excite the nuclear magnetization in other slices. This result in an overall measuring time which is determined by the resolution and the repetition time. When the nuclear magnetization distribution in the individual slices of the volume is to be determined with a resolution of 128.times.128 pixels, and the repetition time amounts to 1 second, the measuring time is still more than 2 minutes.